Michael Boyd

U.S. Environmental Protection Agency

Member of ICRP Committee 4

Third International ICRP Symposium

Seoul, Korea

20 October 2015

This presentation represents the author’s views and

opinions. It does not necessarily reflect the official

positions of the U.S. Environmental Protection Agency or

other federal and state agencies involved with managing

contaminated sites in the U.S.

This presentation has neither been approved nor endorsed

by the Main Commission of ICRP.

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� In the U.S., radioactively contaminated sites may be

managed by local and state authorities or, at the federal

level, by the Department of Energy (DOE), the Nuclear

Regulatory Commission (NRC), the Department of

Defense (DoD), or the Environmental Protection Agency

(EPA), among others.

� This presentation focuses on sites where EPA either has

the lead or has had significant input into cleanup

decisions.

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� Radium (and vanadium) sites from early 20th century

� Sites contaminated from atomic energy and nuclear

weapons development programs (includes Manhattan

Engineer District (MED) sites and Atomic Energy

Commission (AEC) sites)

� Uranium mill tailings sites

� Sites contaminated from previously allowed practices or

small accidental releases (includes nuclear, industrial,

medical, research and military uses of radioactive

material)

� Sites containing naturally occurring radioactive material

(rare earth mining, oil and gas industry)4

� No federal laws and regulations specifically addressed cleanup of radioactively contaminated sites until 1970s

� Legacy uranium milling sites and vicinity properties are cleaned up under the Uranium Mill Tailings Radiation Control Act of 1978 (UMTRCA)

� UMTRCA is an amendment to Atomic Energy Act (AEA)

� EPA and DOE may both use the process defined in the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) for managing site cleanups

� EPA implements CERCLA through the Superfund Program

� CERCLA/Superfund applies to all hazardous pollutants at a site

� NRC regulations for cleanup and decommissioning of their licensed facilities are under their AEA authority

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� Uranium Mill Tailings Radiation Control Act (1978)

� Covers inactive and active U mill sites

� UMTRCA identified 22 inactive mill sites

� Using UMTRCA authority, EPA established cleanup

standards for sites contaminated with buried and wind-

blown tailings (40 CFR part 192, subpart B)

� General cleanup standard for Ra-226 in soil is 185 Bq/kg (given as 5 pCi/g) in top 15 cm; 555 Bq/kg below 15 cm (same value for Ra-228 at thorium sites)

� 555 Bq/kg viewed as a finding tool for locating buried tailings, which were generally much higher in concentration

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� EPA’s Superfund Program implements CERCLA

� CERCLA cleanup process is sometimes used by other agencies outside the Superfund program

� For cleanup under Superfund, a site must first be listed

on the National Priorities List (NPL)

� NPL listings are determined by a Hazard Ranking System score (for all onsite contaminants except natural background)

� Cost of cleanup is shared by responsible parties (“polluter pays” doctrine), but the Superfund Program covers the cost of cleanup when no liable parties are identified

� Superfund funding mechanism allows for stringent risk

reduction goals to be achieved

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� Preliminary Assessment/Site Investigation

� Initial site assessment

� National Priorities List (NPL) Site Listing Process

� Uses Hazard Ranking System to identify highest priority sites

� Remedial Investigation/Feasibility Study

� Site characterization phase; includes baseline risk assessment

� Determination of options for remediation

� Records of Decision (remedy selection)

� Final Steps: Cleanup activities, post-cleanup reviews,

eventual removal from the NPL

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� Except for mill tailings sites, most EPA radiation site

cleanups are carried out using the CERCLA process

� Following cleanup, target residual risk goal is 10-4 to 10-6

excess cancers

� No more than ~ 1 lifetime excess radiogenic cancer among 10,000 individuals exposed at the cleanup level (95th

percentile lifetime exposure duration is 25 to 30 years)

� At current risk estimates, this equates to a cleanup goal of around 100 to 150 µSv per year to a reasonably maximally exposed individual

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� ICRP Pub. 103 recommends public dose reference levels for existing site cleanups in the range of 1 to 20 mSv/a, with optimization below the reference level

� CERCLA-based regulations in the U.S. result in radiation site cleanup goals that yield public doses that are typically 10 to 100 x lower than this range (i.e., in the lower end of ICRP recommended range for planned exposures)

� Cleanup goals generally set based on unrestricted future use

� When unrestricted future use is not achievable, risk objectives may be met by limiting future site use to commercial/ industrial activities or other restricted access uses (park, game preserve, etc.)

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� Curies discovered radium (RaCl) in 1898

� Some rare earth mining (e.g., vanadium) left behind radium in tailings

� Many radium sites associated with early 20th century uses and misuses of radium

� Radio-luminescent dials

� Medical treatments (some legitimate) and quackery

� Radium research activities

� Many contaminated sites ignored or not discovered until mid-20th century or later

� Radium sites now cleaned up following CERCLA process

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� 1924 – 1944: University of Pennsylvania physics

professor enriched radium ore in his home

� 1964: Pennsylvania Department of Health performs

partial cleanup

� Pennsylvania informs EPA of site in 1983 and it is listed

on NPL in 1985; Cleanup is federally funded

� Threat from radium and radon assessed in house and

vicinity property

� Result: removal of 1,300 metric tons of contaminated

building rubble and 3,700 metric tons of contaminated

soil; Site removed from NPL in 1991

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� 469 residential properties and ten municipal properties (total of ~50 hectares) contaminated from nearby radium processing facilities that operated in early 1900s

� State of New Jersey discovered high indoor radon and gamma levels in 1983; listed on NPL in 1985

� Estimated that 170,000 m3 of radium-contaminated soil was spread across the site over time

� Remedy involved excavation and off-site disposal of all radium-contaminated soil, followed by restoration of the properties (some residents temporarily relocated)

� Cleanup began in 1990, was completed in 2004, and site was removed from NPL in 2015

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� Program started in 1974 to address sites with

contamination resulting from U.S. atomic energy and

nuclear weapons programs (1940s – 1960s)

� Sites contaminated with low levels of uranium, thorium and radium, and their decay products

� Cleanup responsibility transferred from U.S. Department

of Energy (DOE) to the U.S. Army Corps of Engineers

(ACE) in 1998

� Sites being cleaned up using CERCLA process

� Following cleanup, sites transferred to DOE Legacy Management Program

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� Site was used by MED/AEC from 1947 – 1952 to store

residues from uranium ore processing

� Site is 77 hectares on federal land

� Radioactive waste is impounded in a 4 hectare interim

waste containment structure

� 184,000 m3 of soil contaminated with U-238, Th-230, Cs-137,and Ra-226; includes ~3,000 m3 of Ra-226 at 19 MBq/kg (legacy Belgian Congo ore)

� US ACE is in charge of ongoing site management and cleanup activities

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� EPA regulations under Superfund and UMTRCA have

guided the cleanup of most legacy radiation sites since

~1980s

� Cleanup of existing exposure situations in the U.S. often

results in residual doses to the public well below ICRP

Pub. 103 reference levels

� EPA’s management of contaminated sites uses the ICRP

process of optimization to determine cleanup goals

� Superfund baseline risk assessments for determining risk-based cleanup goals rely on ICRP biokinetics and dosimetry

� Legacy radiation site management in the U.S. is a

continuing effort19

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